Turbines, in particular in motor vehicle construction, are known from the prior art in connection with gas turbochargers having a turbine rotor rotatably mounted in a housing, which is associated with a least one guide apparatus forming a radial inlet channel for a medium driving the turbine rotor. In motor vehicle construction turbochargers are used to increase the power and the rotational moment of a combustion engine. The turbine more specifically the turbine rotor of the turbine of such an exhaust gas turbocharger is driven by an exhaust gas flow of the combustion engine and in turn drives a compressor which in turn compresses and drives drawn-in fresh air into the cylinders of the combustion engine. By compressing the fresh air the fresh air component introduced in the cylinders of the combustion engine is increased and the power and rotational moment increase achieved as a result. Since the turbine is driven by the exhaust gas of the combustion engine no additional units for increasing the charging volume of the cylinders are necessary. In the meantime, turbines are also used which have a so-called variable turbine geometry (VTG). Turbines with variable turbine geometry are based on the mode of operation of the Francis turbine and serve to better or optimally adjust/adapt the power output and the response characteristics of the turbine or the exhaust gas turbocharger to different points of operation. To achieve this, a turbine with variable turbine geometry comprises a guide apparatus assigned to the turbine rotor and which forms a radial inlet channel for the medium (in this case the exhaust gas of the combustion engine) driving the turbine rotor. In the inlet channel formed by the guide apparatus adjustable guide vanes are arranged which radially surround the turbine rotor. These guide vanes can be adjusted with respect to their vane angle to change the flow cross section of the inlet channel. Usually, the guide vanes are distributed evenly or at equal angles over the circumference of the turbine rotor and, spaced from this, on a guide vane bearing ring of the guide apparatus. The vane angle of the guide vanes for example is set in such a manner that with a low throughput of the medium driving the turbine rotor and with simultaneously high power requirement the flow cross section in the inlet channel is reduced so that the medium is directed onto the turbine vanes in an accelerated manner, as a result of which the rotational speed of the turbine and thus the power of the compressor or the exhaust gas turbocharger is increased. Conversely, with a high throughput of the medium and a low power requirement, the flow velocity of the medium can be reduced through a large flow cross section, as a result of which the power of the turbine and thus that of the exhaust gas turbocharger is reduced.
From the European Patent Publication EP 0160460 B1 a turbine as described above is known, wherein the vane bearing ring is mounted axially displaceably and, together with a housing section of the housing of the turbine, axially delimits the inlet channel.
From EP 1 536 103 A1 a generic turbine is known, wherein however a vane bearing ring and an associated cover disc are connected to each other in a fixed manner via a pin 35.
From WO 2007/046798 A1, from EP 1 816 317 A2 and from WO 2004/109063 A1 additional turbines are known.